Noiseless platen for typewriting machines



April 8, 1947. U CONARD 2,418,698v

NOISELESS PLATEN FOR TYPEWRITVING MACHINES Filed May 22, 1944 {NVENTORl :Fu Mick u. @Manuf BY I 7 Patented Apr. 8, 1947 NOISELESS PLATEN FOR TYPEWRITING MACHINES Frederick U. Conard, West Hartford, Conn., assignor to Underwood Corporation, a corporation of Delaware Application May 22, 1944, Serial No. 536,829

(Cl. 12W-147) 3 Claims.

This invention relates to platens for typewriters and like machines, which function as a part of the paper-feed mechanism, holding the paper on a letter-feedable carriage and backing same for receiving the type impressions.

The main object of the invention is to provide an improved platen, for these purposes, which materially reduces the noise of the type impact on the paper, while affording adequate backing for the paper so as to produce clear type impressions.

A further object resides in providing a platen of such construction that Vibrations set up in the platen incident to striking of the type therewith are minimized, and the tendency of transmitting these vibrations to other portions of the typewriter where they may be amplided is substantially obviated.

More specifically, the platen of the invention comprises a series of plate-like members preferably of uniform, letter-space thickness and arranged side by side in a continuous array through the effective length of the platen. These members, herein shown as disks, are resiliently supported so as to yieldingly recede slightly under impact or pressure of a type face impressed against the work sheet. The construction is such that these disks may recede individually7 and thus solely receive the type impact. Therefore the resultant vibrations are conned substantially to a minor portion of the platen and are thereby isolated from the rest of the platen and from other portions of the typewriter. A resilient cylinder of rubber or like material may be provided over the disks to augment the sounddeadening effect and assist in their resilient support, the outer cylinder serving also to avoid marking of the carbon copies by the disks adjacent the receding one.

With these and other objects in view, the in- Vention will now be described with reference to the accompanying drawings, showing one embodiment which the invention may assume in practice. In the drawings:

Figure 1 is a side elevation, as Viewed just inside the carriage end, of the related portion of a typewriter embodying the invention;

Figure 2 is an enlarged View of the platen roll of the invention, shown partly in central section, and

Figure 3 shows the action of the platen under impact of the type, the eifect being somewhat exaggerated for the purposes of illustration.

The invention has advantageous application in typewriters in which, as shown in Figure l, a

2 platen roll 5 is rotatably mounted on a paper carriage 6 arranged to travel relatively to a printing point at which the actuated one of a complement of type bars 'l strike the work sheet 8 held in place around the platen by usual devices, not shown. In typing a line the carriage 6 is caused to advance in uniform letter-feed steps under control of a suitable escapement mechanism S, and the paper traverses the printing point to receive the type impressions seriatim. Rotation of the platen in selective increments by the usual devices, not shown, effects linefeeding of the paper.

Referring to Figure 2, the platen 5 may be rotatably supported on the carriage by a shaft I0 journaled in the end members of the carriage 6. A core or sleeve i l of highly resilient material, such as rubber, is provided on the shaft. A plurality of rigid plate-like members or disks l2 are placed side by side in contact with each other on the core. The thickness of each disk should be substantially equal to the length of the uniform letter-feed steps taken by the carriage, within tolerances such that each disk will be substantially aligned with the type as the platen is stepped past the printing point.

The disks l2 all have the same outside diameter and each has a central hole in which the core ll ts snugly. The core Il thus aligns the disksof the entire series with each other to form a composite rollof uniform diameter throughout. The disks l2 are preferably straight in transverse section, presenting flat sides each in contact over substantially the entire area with 'the side of the adjacent disk. The disks may be made of various rigid or non-resilient materials, preferably also aifording characteristics of light weight, low cost, and economie manufacture. Good results are obtained by using disks of plastic material such as Bakelite or Phenolite, which also have an inert or sound dampening character advantageous in reducing vibrations.

At each end of the series of disks a wooden or like collar i3 is provided to which a flanged hub iii is secured by means such as screws I5, as shown. The collars i3 are held against the respective end-most disks by having the hubs I4 secured in position on shaft lil by set screws I6.

Over the entire roll thus constructed, an outer cylinder Il of rubber or like resilient material is provided. This cylinder may be slightly smaller in inside diameter than the disks l2 so that in assembled relation the rubber cylinder is Iightly tensioned circumferentially against the disks. At its ends the outer cylinder I1 is suitably secured to each collar l 3 as by nails I 8 driven into they collars.

In Figure 3, the action of the platen under irnpact or pressure of the type is shown, the effect being greatly exaggerated for purposes of illustration. It will be observed that each disk is resiliently held in its normal position flush with the other disks by two elements; one, the center core Il engaging the edge f the hole in the disk; and, two the outer cylinder Il engaging the periphery of the disk. The force of the type striking the work sheet is imparted to the rubber cylinder ll which, being resilient, may be compressed a slight degree and may also bend transversely es it is distorted against the effective disk I 2. Under this pressure the disk itself recedes slightly, impressing the core I l and eXtruding the cylinder Il at the far side. When the compression of the core and the tension of the cylinder are sufficient to overcome the force of the type bar, the action is reversed, meanwhile the type impression having been imparted to the work sheet through the usual inked ribbon, not shown. As soon as the type .retracts from the Work sheet anda ribbon, the .core .il and cylinder Il restore the receded .disk to normal position ush with the others Incident to the typing operation just described, the carriage takes a letter-feed Istep which advances `the platen so that the next adjacent disk l2 .is .aligned with the printing point. Upon actuating the succeeding type bar, this next disk is eective to receive the impact of the tyl9e- By receding under impact of the type, the effective disc .l2 minimizes vibrations imparted under .impact of the type against the platen. Furthermore Asuch vibrations are not transmitted to adjacent .disks .except possibly to a very limited degree, so that the noises resulting from the type impact are reduced to a minimum. The compa-ct association of the disks engaged one against the .other contributes to the dampening of vibrations .and tends to coni-lne them to a relatively few of the disks at the region of the type impact.

Although only the one embodiment is shown and described. it will be understood that the invention may be modified or embodied -in various other forms without departing from its spirit or the 'scope of the appended claims.

What is claimed is:

1. A platen roll for a typewriter or like machine, comprising a plurality of rigid, apertured disks of substantially uniform diameter and thickness, arranged side by side to collectively present an even cylindrical face, means to maintain the disks in sliding contact with each other, allowing edgewise movement of each disk individually, resilient means engaging the apertures of said disks and yieldably supporting said ldisks against edgewise displacement, and an outer cylinder of resilient material engaging the periphe ery of said disks.

2. A platen roll for a typewriter or likemachine, comprising a plurality of rigid, apertured disks ef substantially uniform diameter and' thickness, arranged side by side to collectively present an even cylindrical face, means to maintain the disks in sliding contact with each other, allowing edgewi'se movement of each disk indi- Vidually, .a resilient core snugly fitting the apertures of said disks, and an outer cylinder of resilient material engaging the peripheries of said disks, said core and said outer cylinder jointly icesliting yieldably edgewise displacement of said is s.

3. A platen for a typewriter or like machine, comprising an elongate shaft, a sleeve of resilient material on said shaft, a series of apertured disks of substantially uniform letter-space thickness arranged side by Side on said sleeve, the series of disks extending over the ei-ective length of the platen, collars, one at each platen end, secured to said shaft and holding said disks in sliding contact with each other, and an outer, resilient cylinder over said disks and secured at its ends to said collars.

. FREDERICK U. CQNARD.

REFERENCES CITED The following references are vof record in the file of this patent:

UNIT-ED STATES PATENTSv 

